Two years ago I cut down a crepe myrtle that was growing in a wrong spot. I dug out a lot of the root ball 1 1/2 years ago but I'm still getting sprouts from this plant. I've used a combo of digging out and spraying with Roundup the new shoots but it doesn't seem to go away. I want to plant other things in this area but I want all remnants of the crepe myrtle gone before planting other items.